The present invention relates to movement amount operation correction processing for correcting a correction value when calculating an amount of movement of a stage for bringing a probe of a probe card into contact with an electrode in a prober used to inspect a semiconductor device (chip) with a tester.
A semiconductor manufacturing process has a number of processes and various inspections are carried out in various manufacturing processes in order to maintain the quality and improve the yield. For example, at the stage in which plural chips of semiconductor device are formed on a semiconductor wafer, a wafer level inspection is carried out. In this inspection the electrode of the semiconductor device of each chip is connected to a tester, power and a test signal are supplied from the tester, the signal output from the semiconductor device is measured with the tester, and whether each chip operates normally is checked electrically.
After the wafer level inspection, the wafer is bonded to a frame and cut into individual chips by a dicer. Only the cut chips that have been confirmed to operate normally are packaged in the next assembling process and the defective chips are removed from the assembling process. Further, the final packaged products are subjected to an inspection on shipping.
FIG. 1 is a diagram showing a general configuration of a system for carrying out a wafer level inspection. The system for carrying out a wafer level inspection comprises a prober for bringing a probe 11 into contact with an electrode of each chip on a wafer and a tester 5 electrically connected to the probe and supplying power and a test signal to each chip for an electrical inspection and, at the same time, detecting the output signal from each chip to measure whether each chip operates normally. Reference numbers 1 to 4 denote parts constituting a case of the prober. To an upper plate 4, a probe card 12 having the probe 11 that comes into contact with an electrode and a wafer alignment camera 13 are attached. A base section 1 is provided with a moving mechanism 24 for moving a stage 22. The stage 22 is provided with a wafer chuck 21 for holding a wafer 100 by means of vacuum adsorption and a probe position camera 23 for detecting the position of the probe 11 of the probe card 12. The wafer chuck 21 is capable of not only moving in three-axis directions by means of the moving mechanism 24 but also rotating about an axis in the vertical direction as a center. There may be a case where the wafer alignment camera is attached to a support plate 3 of the case.
The tester 5 is mounted on the upper plate 4 of the case of the prober. The electric terminal of the tester 5 is connected to the terminal of the probe card 12 and electrically connected to the probe 11. The tester 5 and the prober are separate products and a user configures a wafer level inspection system by adequately combining the tester 5 and the prober in accordance with a chip formed on a wafer. Further, it is necessary for the probe card 12 to comprise a probe 11 arranged in accordance with an electrode of a chip to be inspected and the probe card 12 is adequately exchanged in accordance with the chip (semiconductor device).
An image photographed by the wafer alignment camera 13 and the probe position camera 23 is sent to an image processing/operation processing section 31. The image processing/operation processing section 31 detects the position of the electrode of each chip of the wafer 100 held by the wafer chuck 21 from the image of the wafer alignment camera 13 and detects the position of the probe 11 of the probe card 12 from the image of the probe position camera 23. The image processing/operation processing section 31 sends data about the detected position of the electrode of each chip and the position of the probe 11 of the probe card 12 to a movement control section 32. The movement control section 32 has a movement amount operation section 33 for calculating the amount of movement of the stage 22 necessary to bring a predetermined position of an electrode into contact with the probe 11 based on the data etc. The movement control section 32 controls the moving mechanism 24 based on the amount of movement calculated by the movement amount operation section 33 and brings the electrode into contact with the probe 11 by moving the stage 22.
By the way, only the movement control section 32 is shown here but, in reality, a control section for performing various controls of temperature adjustment, rotation of the wafer chuck 21, etc., is provided and the movement control section 32 is configured as part of the control section. The control section is constituted by a computer. Further, the image processing/operation processing section 31 displays the image of the wafer alignment camera 13 and the image of the probe position camera 23 on a display device 34 without any processing or after image processing. An operator performs various settings and operations while watching the image on the display device 34.
FIG. 2 is a diagram showing a configuration of the portion of the probe card 12. The upper plate 4 of the case of the prober is provided with a head stage 15 and the head stage 15 is provided with a cardholder 14. The probe card 12 having the probe 11 needs to be exchanged in accordance with a chip to be inspected as described above, and is detachably attached to the cardholder 14.
When bringing the probe 11 into contact with an electrode, after moving the wafer chuck 21 holding the wafer 100 such that the electrode is located immediately under the probe 11, the electrode is brought into contact with the probe 11 by lifting the wafer chuck 21. At this time, by applying a voltage to the terminal of the tester to be connected to the probe 11, it is made possible to detect that the probe 11 has come into contact with the electrode, then the wafer chuck 21 is controlled to stop ascending.
As described above, the configuration of a conventional wafer level inspection system has been explained. However, the wafer level inspection system is described in, for example, Japanese Unexamined Patent Publication (Kokai) No. 10-150081, Japanese Unexamined Patent Publication (Kokai) No. 2002-170855, Japanese Unexamined Patent Publication (Kokai) No. 2004-79733, etc. and, therefore, a further explanation is omitted here.
Recently, semiconductor devices (chips) have become more highly integrated and reduced in size and, in accordance with this, the size of an electrode and the intervals in the arrangement have been reduced. Because of this, it is demanded that the precision of the alignment of the probe 11 and an electrode be about ±2 μm. As described above, the arrangement of the probe 11 of the probe card 12 differs from chip to chip to be inspected and it is necessary to exchange the probe card 12 in accordance with the chip to be inspected. The probe card 12 is attached by engaging it with the cardholder 14, however, the positional precision is specified by the errors of the engagement and it is not possible to realize the precision of ±2 μm described above. Further, the probe itself can have errors of position. Furthermore, the probe is made of a thin spring material and if contact with the electrode is repeated, the position of the probe will change. On the other hand, a wafer is held by a wafer chuck by means of vacuum adsorption etc., however, it is not possible to hold the position with high precision.
Therefore in the prober, as shown in FIG. 1, the wafer alignment camera 13 photographs each chip of the wafer held by the wafer chuck and the position of electrode of each chip is recognized by image processing. The wafer alignment camera 13 photographs a microscopic image of the chip and it is possible to recognize the position of the electrode with high precision. Similarly, by performing image processing of the image of the probe 11 of the probe card 12 photographed by the probe position camera 23, it is possible to recognize the position of the probe 11 with high precision.
FIG. 3A to FIG. 3D are diagrams for explaining operation processing of the amount of movement for bringing the electrode into contact with the probe 11 based on the position of the electrode and the position of the probe 11 recognized as described above. Here, the operation of the amount of movement only in the direction of one axis (X-axis) is explained, however, this similarly applies to the directions of the other two axes.
FIG. 3A shows a state in which the axis of the wafer alignment camera 13 coincides with the axis of the probe position camera 23. In other words, it shows a state in which the origin of the image of the wafer alignment camera 13 coincides with the origin of the image of the probe position camera 23. It is assumed that the moving mechanism at this time indicates a movement position R. It is not necessary for the moving mechanism to be capable of moving until the axis of the probe position camera 23 actually coincides with the axis of the wafer alignment camera 13, and it is only necessary to be capable of specifying the movement position R of the moving mechanism when the axis of the wafer alignment camera 13 virtually coincides with the axis of the probe position camera 23.
Next, as shown in FIG. 3B, the probe position camera 23 is moved to under the probe 11A of the probe card 12 and the position of the probe 11A in the image of the probe position camera 23 is detected. Actually, the probe of the probe card 12 is provided in plural in accordance with the number of electrodes of the chip and the positions of all of the probes are detected. Here, for simplicity of explanation, it is assumed that the probe is single and is located at the origin of the image of the probe position camera 23 and a movement position S1 of the moving mechanism at this time is S1. Therefore, the distance between the axis of the wafer alignment camera 13 and the probe 11A is S1-R.
Next, as shown in FIG. 3C, the wafer 100 is moved to under the wafer alignment camera 13 and after the wafer chuck 21 is rotated such that the arrangement direction of the electrode of the chip coincides with the arrangement direction of the probe 1, the position of the electrode of the chip is detected. As plural electrodes of the chip are provided, the positions of all of the electrodes are detected. By the way, a plurality of chips are formed on the wafer 100 and it is necessary to detect the position of the electrodes of each chip, however, there may be a case where the position of the electrodes of some of the chips are detected and the position of the electrodes of the other chips are calculated by operation because actually, the chips are regularly arranged with high precision.
In the case of plural electrodes, plural probes are arranged at corresponding positions for plural electrodes and whether the plural electrodes can be brought into contact with the plural probes is judged and further the positional relationship between all of the electrodes and all of the probes is calculated. As the position of each electrode varies and the position of each probe also varies, the positional relationship is one in which the difference of each probe from the predetermined position of the corresponding electrode is a minimum, as a whole. This positional relationship does not relate directly to the present invention and, therefore, it is assumed here that the electrode is one and is located at the origin of the image of the wafer alignment camera 13, and a movement position of the moving mechanism at this time is S2.
The electrode is located at the origin of the image of the wafer alignment camera 13 and, in order to bring the electrode into contact with the probe 11A S1-R away from the origin of the image of the wafer alignment camera 13, it is necessary to move only by S1-R from the state in FIG. 3C, that is, the state in which the movement position of the moving mechanism is at S2. FIG. 3D shows a state in which the movement position of the moving mechanism is at S1+S2-R, and the electrode of the chip at this time is located immediately under the probe 11A, therefore, if the wafer is lifted from this position, the probe 11A comes into contact with a predetermined position of the electrode.
The amount of movement to bring the electrode into contact with the probe of the probe card is calculated as described above, however, the precision of the amount of movement is affected by the positional relationship between the wafer alignment camera 13 and the probe position camera 23, the detection precision of the wafer alignment camera 13 and the probe position camera 23, the movement precision of the moving mechanism, etc.
The moving mechanism is capable of high precision control, however, if it is aimed to maintain a high precision across a wide movement range, there arises a problem in that the cost is increased accordingly. Therefore, movement with a high precision is realized in the moving mechanism by measuring errors for the movement distance in advance to store the amount of correction in a correction table of the movement amount operation section 33 and by performing correction in accordance with the movement position.
If the error measurement for the movement distance for creating the above-mentioned correction table is performed in an actual prober, the amount of correction including the positional relationship between the wafer alignment camera 13 and the probe position camera 23 is calculated as a result.